The present invention relates to surface-grinding of workpieces.
In particular, the present invention relates to methods and apparatus for surface-grinding workpieces with a ring-shaped grinder having a ring-shaped grinding surface the inner diameter of which is relatively large as compared with the dimensions of the workpieces.
With known surface-grinding machines of the above general type, for providing workpieces of the most varied materials with flat surfaces, it is customary to achieve the required degree of grinding by way of multiple adjustment of the grinding wheel with respect to the work, or adjustment of the work with respect to the grinding wheel, so that in this way it is possible on the one hand to achieve an accurate grinding and on the other hand to provide a precisely plane ground surface of desired smoothness at the work. Thus with conventional methods and apparatus the work is carried either by a longitudinally oscillating worktable or by a rotating circular worktable, such a worktable serving to hold the workpieces, while the feed of the grinding wheel and the work one with respect to the other is carried out after each reciprocation of a longitudinally moving worktable or after each revolution of a rotary worktable.
It is also known to provide surface-grinding machines where there is a combination of a longitudinally reciprocating and rotating worktable, with the rotary movement of the circular worktable being superimposed upon the straight-line reciprocation of the longitudinal table, the grinding wheel being carried by a carriage which is perpendicularly adjustable with respect to the direction of movement of the worktable.
Also, there are known surface-grinding machines where a ring-shaped grinding wheel has its axis situated at an inclination which is somewhat different from perpendicular to the worktable, on the one hand in order to reduce the power required during preliminary grinding with a relatively great cut, while on the other hand it is possible with such machines to provide cylindrical workpieces such as rings, discs, or cutting blades or the like with side surfaces which are inclined with respect to each other from the inside toward the outside. In addition it is already known to provide for workpieces whose outer dimensions are small with respect to the inner diameter of the ring-shaped grinding surface a movement on the circular or longitudinally movable worktable according to which the grinding surface is crossed twice by the workpiece at different locations of the grinding surface.
With the above conventional methods and apparatus a number of difficulties are encountered. Thus, with these conventional methods and apparatus the power required for bringing about the surface-grinding is excessively large while at the same time the time required for grinding workpieces is much too long. In addition, problems are encountered in maintaining the dimensions of the ground workpieces within predetermined tolerances. Also, the supply of cutting fluid to the workpieces while they are ground is provided in many cases only with considerable difficulty.